${ 1.39 \times 2 = {?}} $
Solution: ${1}$ ${3}$ ${9}$ ${2}$ ${0}$ ${\times}$ ${.}$ ${.}$ ${0.09}\times {0}= {0}$ ${0}$ ${0.3}\times {0}= {0}$ ${0}$ ${1}\times {0}= {0}$ ${0}$ ${0.09}\times {2}= {0.18}$ ${8}$ ${0}$ ${0.3}\times {2}+{0.1}= {0.7}$ ${7}$ ${1}\times {2}= {2}$ ${2}$ ${+}$ ${2}$ ${7}$ ${8}$ ${0}$ $\text{The top number has 2 digits to the right of the decimal.}$ $\text{The bottom number has 1 digit to the right of the decimal.}$ $\text{The product has 2 + 1 = 3 digits to the right of the decimal.}$ ${.}$ ${ 1.39 \times 2.0 = 2.780} $